chore: release Myna 0.30.0

[ralyodio]

Bumps all six version files to 0.30.0 so the next tag covers #92 (the port of #90: crawlproof tracking, A/B variants, stats, quoted-printable). #92 merged after v0.29.1 without a bump, so main has been reporting 0.29.1 without matching that tag.

Checked on main + this bump:

• tsc clean
• CI test line: 560 pass, 0 fail
• API tests against local Postgres: 27 pass
• CLI run against a local fake SMTP server:
  • create with an A/B subject: 8 variants
  • dry run
  • --to test copy
  • a list send without --yes refuses
  • --yes sends 3 messages; a rerun sends 0
  • every message carries List-Unsubscribe + List-Unsubscribe-Post and the postal address
  • myna email --list still works

After merge: tag v0.30.0, check the release files, rebuild the local binary, and announce.

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